Question: Which of these numbers is composite? ${31,\ 71,\ 79,\ 83,\ 98}$
A composite number is a number that has more than two factors (including 1 and itself). 31, 71, 79, and 83 each have only two factors. The factors of 98 are 1, 2, 7, 14, 49, and 98. Thus, 98 is the composite number.